|Abstract ||ABSTRACTMyoglobin was exposed to acetone (50–99%) in three different ways. The wettability of the resulting preparations was determined by a screening method as well as by contact angle measurements, while the surface pressure was characterized by the decrease in surface tension of water. The wettability of the preparations could be ascribed to the surface properties of the fraction of the preparations which had undergone irreversible transition. Several other factors including roughness of the preparation, microstructure and amount of native-like molecules also had a significant influence on the apparent wettability. The surface pressure could be correlated to the amount of native-like molecules in a preparation, but was also influenced by the wettability of the preparation.